Manufacture of glutamic acid and salts thereof



, mized if the digestion of Patented Apr. 27, 1926.

UNITED STATES KIKUNAI E Z IKEDA, OF TOKYO, JAPAN.

I MANUFACTURE OF GLUTAMIC ACID AND SALTS THEREOF.

No Drawing.

To all whom it may concern:

Be it known that I, Dr. KIKUNAii IKEDA, a subject of the Emperor of J apan, residing in Tokyo, Japan, have invented certain new and useful Improvements in the Manufacture of GlutamicAcid and Salts Thereof, of which the following is a specification.

The present invention is for improvements in and relating to the manufacture of glutamic acid and salts thereof, and has particular reference to the manufacture of this acid from schlempe, a by-product of the manufacture of alcohol from beetroot molasses.

In brief, the production of schlempe consists in diluting the beetroot molasses, elf-ecting the fermentation thereof and distilling 0d the alcohol. The residue in the still is then concentrated, generally to a specific gravity of 1.40, and the syrupy substance so obtained constitutes the schlempe as it usually comes upon the market. The present invention is, however, not restricted to the use of schlempe produced in a particular manner, but is applicable to any residue from beet-sugar manufacture which contains glutamic acid either as such or as part of a more complex molecule.

According to the present invention, the process for the manufacture of glutamic acid from schlempe is characterized by recovering the acid in the form of its sparingly soluble calcium salt.

Thus, the liquor may be digested with an excess of lime, pounds of glutamic acid, and the formation of its calcium salt is effected in a single operation. Considerable care, however, is needed in adopting this procedure, because the optically active acid is liable to be racethe liquor with the lime be carried out .at too high a temperature or be too prolonged. It is, therefore, preferred first to digest the schlempe with an acid hydrolytic reagent such as a mineral acid,'for example, sulphuric or 11ydrochloric acid, and then to treat the neutralized solution with lime for the pur pose of converting the glutamic acid into the calcium salt.

An alternative method is to convert the glutamic acid into the hydrochloride, and

then to treat this with lime for the purpose of forming the calcium salt.

. From the calcium salt, the free acid may be readily obtained, or the salt. may be Application filed January 5, 1925. Serial No. 680.

whereby hydrolysis of com-.

treated with the salt of an alkali thev acid radicle of which combines with calcium to give a calcium salt insoluble, or substantially insoluble, in water.

The following isa description by way of example of the operation of the invention.

The schlempe, which, if of the usual syrupy consistency, it is desirable to dilute, is heated with sulphuric or hydrochloric acid in order to hydrolyze glutamine and like compounds and to liberate glutamic acid. The acid gives rise to humuslike substances, which are filtered off, and the liquor is then neutralized with lime.

lVhen sulphuric acid has been used as the hydrolytic reagent, the calcium sulphate which is produced on neutralization is filtered off, and the liquor is then'decolorized by means of animal charcoal, or any other suitable decolorizing agent. The liquor is then digested with an excess of lime, filtered while still warm and evaporated to low bulk, the last-mentioned procedure being most advantageously carried out under reduced pressure. On standing, crystals of the calcium salt of the bibasic glutamic acid, having the composition C H,NO,Ca,H O, gradually separate out. These crystals are collected and Washed with cold water to free them from the mother liquor, this operation involving no material loss owing to the difficult solubility of the salt in cold water.

As previously stated, the glutamic acid may be initially isolated'in the form of the hyc rochloridc. For this purpose, the liquor from the acid hydrolysis, neutralized, and freed from calcium sulphate, is evaporated almost to dryness, and then admixed with fuming hydrochloric acid in excess. On

standing, glutamic acid hydrochloride, to-

getherwith potassium chloride and other substances, crystallizes out. The whole crystalline mass is freed as far as possible from mother liquor, dissolved in water, the solution digested with an excess of lime, filtered Warm, and the filtrate put by for crystallization. The dillicultly soluble calcium glutamate, C H NO Ca,H O, graduaL ly separates out, somewhat discolored, but otherwise of good commercial purity.

If hydrochloric acid has been originally used as the hydrolytic reagent, the hydrolyzedschlempe filteredfrom humus-like substances, is concentrated by evaporation to a syrupy condition and then left to crystallize.

, It is advantageous to add some hydrochloric acid, either in the form of a concentrated solution, or as the gas. In a few days, almost the whole mass becomes crystalline, and on separatin the mother llquor crude glutamic acid hyd rochloride is obtained, and on decomposition with lime as previously described gives substantially pure calclum glutamate.

This modified form of procedure, whereby glutamic acid hydrochloride is prepared as an intermediate product, requires a considerable quantity of concentrated hydrochloric acid, but enables the employment of a decolorizing agent to be dispensed with, or the quantity to be reduced.

The separation of the difficultly soluble calcium glutamate may be facilitated by the addition of alcohol, the presence of which also somewhat increases the yield, and the addition of a soluble salt of calcium and some free ammonia accelerates the formation of the crystals.

In order to prepare glutamates of alkali metals, the salt of an alkali metal of the type previously mentioned is added in an equivalent quantity to the sparingly soluble calcium salt in presence of water. For instance, with bicarbonate of sodium the following reaction will take place:

On filtering off the calcium carbonate and evaporating the solution, sodium glutamate is obtained in the crystalline state.

The readily soluble calcium salt, of glutamic acid may be prepared by acting with carbon dioxide upon the difiicultly soluble calcium glutamate in presence of water- On removal of the calcium carbonate, and evaporation of the solution the more soluble calcium salt is obtained in crystalline form.

It will be appreciated that the above description is by way of example only and that the invention is not limited thereby. For instance, while I have found lime to be the most convenient 1' agent wherewith to effect the recovery of tle glutamic acid, the equivalents of lime, such as baryta and strontia, are to be regarded as comprised by the term lime, and as being within the scope of this invention. Also in the decomposition of the calcium salt for the purpose of obtaining glutamates of "the alkali metals,

used in place of the bicarbonates other acid salts formed by the combination of alkalies with acids the neutral culeium salts of which are insoluble, or substantially insoluble, in water, for example, the acid oxalate of sodium.

What I claim as my invention and desire to secure by Letters Patent is:

1. The process of manufacture of .glutamic acid and salts thereof from schlempe, characterized by hydrolyzing the schlem e and converting the glutamic acid into t e sparingly soluble calcium salt.

2. A process according to claim 1, wherein the schlempe is digested with excess of lime, preferably at as low a temperature and with the shortest heating possible consistent with hydrolysis of the schlempe and formation of the calcium glutamate, for the purpose of avoiding, or diminishing the degree of, racemization of the active enantiomorph.

3. A process according to claim 1, wherein the schlempe is hydrolyzed with an acid hydrolytic reagent, for example, a mineral acid, the reaction liquor neutralized, filtered from precipitated matters, and then treated with lime to convert the glutamic acid into the calcium salt.

4. A process according to claim 1, wherein the glutamic acid is first converted into substantially pure hydrochloride, and the latter then decomposed by treatment with lime in order to obtain the sparingly soluble calcium glutamate.

5. In the manufacture of glutamic acid according to claim 1, the addition to the liquor containing the sparingly soluble calcium glutamate of a salt of calcium and some free ammonia, for the purpose of promoting the crystallization of the sparingly soluble salt.

6. The process of manufacture of soluble salts of monobasic glutamic acid, which consists in treating the sparingly soluble calcium glutamate obtained by a process as set forth in claim 1 with an acid salt formed by the combination of an alkali with an acid the neutral calcium salt of which is insoluble, or substantially so, in water, for instance, the bicarbonate of an alkali metal.

7. The process of manufacture of the soluble calcium salt of glutamic acid, which consists in treating the sparingly soluble calcium salt obtained by a process as set forth in claim 1 with carbon dioxide gas in presence of water.

In testimony whereof I affix my signature.

KIKUNAE IKEDA.

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